Re: [Qemu-devel] q35 migration broken

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Marcel Apfelbaum (marcel@redhat.com) wrote:
> On 04/01/2016 06:54 PM, Dr. David Alan Gilbert wrote:
> >* Dr. David Alan Gilbert (dgilbert@redhat.com) wrote:
> >>* Dr. David Alan Gilbert (dgilbert@redhat.com) wrote:
> >>>Hi,
> >>>   I'm seeing a breakage on q35 migration on head (and possibly older
> >>>but certainly head; it's also on a 2.5.0 world I've got with a bunch
> >>>of patches but I've not tried a clean 2.5.0 yet).
> >>>
> >>>It looks like some type of interrupt screwup; with a virtio-net device
> >>>I get a:
> >>>   BUG: soft lockup - CPU#0 stuck for 22s!
> >>>   ...  virtnet_config_changed_work
> >>>
> >>>but if I swap that out for an e1000 I get:
> >>>   Disabling IRQ #22
> >>>
> >>>   and various timeouts on e1000 and cdrom (scsi).
> >>>The guest kind of limps along with an existing terminal scrolling dmesg -w output.
> >>>
> >>>This is an f23 guest on a rhel7.2-ish host; with the guest sitting an idle
> >>>(MATE) Gui.
> >>
> >>Also broken with 2.4.1 and 2.5.1 (with pc-q35-2.4 machine type);
> >>see a screen shot attached; note:
> >>    a) The large count on irq 22 (enp2s1) on cpu1
> >>    b) The large count on virtio2-config on cpu1
> >>    c) The count of 'Deferred Error APIC interrupts'.
> >
> >OK, this seems to be the i82801b11-bridge; if I remove it from the config
> >it all works.
> >
> >My minimum config that fails so far is:
> >/opt/qemu-head/bin/qemu-system-x86_64 -nographic -machine pc-q35-2.6,accel=kvm,usb=off,vmport=off -cpu SandyBridge -m 4096 -realtime mlock=off -smp 4,sockets=4,cores=1,threads=1 \
> >  -device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1e \
> >  -drive id=image,file=/home/vms/f23-serial.qcow2,if=none,cache=none \
> >  -device virtio-blk-pci,scsi=off,bus=pci.1,addr=0x5,drive=image,id=virtio-disk0,bootindex=1 \
> >  $*
> >
> >if I flip the i82801b11-bridge for a pci-bridge  then it works.
> 
> Hi Dave,
> That's good news. I see we don't have a vmstate for this bridge, but we do have one for the regular pci-bridge.
> Maybe this is the problem?

Yeh that's one of my suspicions; but how do device classes work?
If a i82801b11-bridge is a subclass of pci-bridge should it just
pick up the vmstate of the subclass magically?

Dave
P.S. I've filed this as RH bz 1323273
> 
> Thanks,
> Marcel
> 
> >
> >Dave
> >
> >--
> >Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> >
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK